The question of whether it is appropriate for nursing mothers to breast-feed in public areas elicits passionate responses on both sides of the argument. Those against it believe breast-feeding should be done in private, saying it makes them uncomfortable to see a mother nursing her child out in the open. Those who support nursing in public contend that the practice is normal, natural and a mother's right.

Kahne found himself in hot water Tuesday when he said on Twitter that a woman's breast-feeding in public was "nasty."

"Just walking though supermarket. See a mom breast feeding little kid. Took second look because obviously I was seeing things. I wasn't! #nasty," the racer said in a tweet to his more than 100,000 followers.

His tweet prompted a firestorm of comments from both men and women, many of whom chastised Kahne for being insensitive, telling him to "grow up." But several others agreed with him. Kahne issued an apology on his Facebook page Wednesday, ESPN.com first reported:

"I understand that my comments regarding breastfeeding posted on Twitter were offensive to some people," Kahne said in a statement. "For that, I apologize. It was in no way my intention to offend any mother who chooses to breastfeed her child, or, for that matter, anyone who supports breastfeeding children. I want to make that clear."

This social media spat comes the same week that "nurse-in" demonstrations have taken place at Target stores across the country.

Michelle Hickman, 35, was asked last month to move into a dressing room when Target employees saw her breast-feeding her baby in the Webster, Texas store. Her story, which was shared on the pro-breast-feeding website, Best for Babes, launched fellow moms into action. Kelly Roth, a nursing mother and a friend of Hickman, started a Facebook group to help organize a "nurse in," which now has 7,500 members.

Hundreds of mothers brought their infants to Targets to nurse together as a group, taking photos of the event and posting them online. "Nurse-in" demonstrations have taken place in 31 states and Canada, according to the Facebook group.

"This is vile. I mean, really? How disgusting. Can't these women use bottles when out in public?," Cheryl said in one comment.

"I don't think that the employees were really that out-of-line asking the woman to simply move into a fitting room. It's not as though they asked her to leave, or not to breastfeed at all. As a woman, that wouldn't bother me in the slightest," another woman posted.

But other comments defended Hickman and nursing mothers: "Most, if not all, of you have eaten in public, yet no one has asked for you to go eat your lunch in the bathroom, or the car, or call you 'vile' or 'attention seeking' when you do it, or asked that your head be covered with a blanket whilst doing so. I am exclusively breast feeding my 6 month old, and I refuse to feed her in a dirty, smelly bathroom, cover her head with a blanket, or feed her in the car (it's winter!)."

Bernice Hausman, an English professor at Virginia Tech who is the author of "Mother's Milk: Breastfeeding Controversies in America" and "Viral Mothers: Breastfeeding in the Age of HIV/AIDS," said "nurse-in" demonstrations have been going on since the late '90s and the outrage over public breast-feeding boils down to "policing women's behavior."

"The biggest question is where women who are mothers are allowed to be. Apparently, mothers are not allowed to be walking around Target," she said. "This sort of public prohibition on nursing in public is about restricting women's freedom by ... making them feel inappropriate."

While breast-feeding is lauded as a "sacred act" done by "the good mother" in private, Hausman said it's seen in public as the woman "wontedly exposing her body."

"The idea that there would be some set of rules about what [women] can and can't do in public when feeding their children is ludicrous," Hausman said.

The American Academy of Pediatrics recommends mothers exclusively breast-feed their babies for six months, and continue nursing for at least one year, or as long as is mutually desired, after introducing solid foods. Forty-five states have laws that specifically allow women to breast-feed in either public or private areas, and 28 states have specific clauses that exempt nursing mothers from public indecency exposure laws.

Full details can be found on the website of National Conference of State Legislatures, a non-governmental organization that provides research for policymakers, HERE.

Hausman said the reason people might be uncomfortable or disgusted by seeing a woman breast-feed in public is that the practice is framed as an intimate moment between mother and child, and when done in public is viewed as a women "subjecting other people to their bodies."

Another issue, Hausman said, is that in our "medically regulated culture," breast milk is perceived as a bodily fluid, and therefore is disgusting and something to be feared.

While some advocates who support public breast-feeding ask that the woman cover herself while doing it as a sort of compromise, Hausman said this was imposing another rule.

"The message is very confusing: 'You should breastfeed, but you should cover up so no one knows what you're doing,'" Hausman said. "The question is, why is it necessary to cover up, why is that such a big issue, when women who are nursing are more covered up than women who are walking on the beach."

"Sesame Street" aired an episode in 1977 when (human) character Buffy breast-fed son Cody in public, without covering the baby, in an effort to explain to Big Bird that the baby was drinking milk from her breast. In a later '70s episode, character Maria explains breast-feeding to another (human) child, while covering herself as she nurses her baby. At the time, it was hailed as a positive, educational way for teaching children about the practice.

Hausman said breast-feeding was at its lowest in the 1970s and there was a huge push at the time to do more education and promote the practice. She added that pro-breast-feeding communities also thought kids should remember being breast-fed, so there were many attempts to include it in children's books and plays.

"It's somewhere in their subconscious that they remember being breast-fed ... and that's important for normalizing it for future generations," Hausman said.